Field of the Invention
The present invention relates to an automatic transmission for vehicles, and more particularly, to a planetary gear train of an automatic transmission for vehicles capable of improving power transfer performance and reducing fuel costs by implementing advance 11-speeds by a minimum configuration.
Description of Related Art
Recently, increasing oil prices have caused vehicle manufacturers all over the world to rush into infinite competition. Particularly in the case of engines, manufacturers have been pursuing efforts to reduce the weight and improve fuel efficiency of vehicles by reducing engine size, etc.
As a result, in the case of an engine, research for reducing weight and improving fuel efficiency by down-sizing the engine has been conducted, and in the case of an automatic transmission, research of simultaneously securing drivability and fuel efficiency competitiveness through multiple speed stages of the automatic transmission has been conducted.
However, in the case of the automatic transmission, as the number of speed stages increases, the number of internal components also increases, and as a result, the automatic transmission may be difficult to mount, the manufacturing cost and weight may be increased, and power transmission efficiency may be deteriorated.
Thus, in order to increase an effect of improving the fuel efficiency by the multi-stage, it may be said that the development of a planetary gear train capable of maximizing efficiency with a small number of parts is important.
In this regard, 8-speed and 9-speed automatic transmissions have been recently implemented, and a research and development into a planetary gear train capable of implementing a shift stage of 8-speed or more has been actively conducted.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.